1. Field of the Invention
The present invention relates in general to closing devices for motor vehicles and more particularly to powered closing devices for closing an automotive back door or the like by the force of an electric power. More specifically, the present invention is concerned with powered back door closing devices of a type which comprises a back door drawing mechanism mounted on a vehicle body and an electric power unit coupled with the back door drawing mechanism for powering the same, wherein when the back door is manually pivoted to an almost closed position, the back door drawing mechanism catches the back door and then enforcedly pulls down the same to a fully closed position.
2. Description of the Prior Art
In order to clarify the task of the present invention, one conventional powered back door closing device of the above-mentioned type will be outlined with reference to FIGS. 13 and 14, which is shown in Japanese Patent First Provisional Publication 4-3026683.
The back door closing device comprises generally a motor mounting plate 1 and a cover base plate 2 which are tightly connected through several struts 3 in a manner to define therebetween a certain space. A latch carrying plate 4 is installed in the space and pivotally connected to the cover base plate 2. The latch carrying plate 4 carries thereon a latch mechanism 5. An electric drive unit 6 is mounted on the motor mounting plate 1. An output shaft 6a of the electric drive unit 6 is connected through a joint mechanism 7 to a pivotally driving mechanism 8 supported by the cover base plate 2. Energizing the electric drive unit 6 induces upward and downward pivotal movement of the latch carrying plate 4 relative to the fixed cover base plate 2.
Upon assembly, the back door closing device is mounted on a rear portion of a motor vehicle where a back door is pivotally arranged, as may be understood from FIG. 1. The back door has a striker secured thereto.
When the back door of the vehicle is manually pivoted down to an almost closed position, the latch mechanism 5 of the closing device latches the striker of the back door and then upon energizing of the electric drive unit 6, the latch carrying plate 4 is pivoted down to pull the back door toward its fully closed position. Upon full closing of the back door, the electric drive unit 6 is deenergized. With this, the back door assumes the fully closed position. When, thereafter, the electric drive unit 6 is energized again, the latch carrying plate 4 is pivoted upward while canceling the engagement of the striker to the latch mechanism 5. With this, the back door is lifted to a released somewhat open position and thus the back door is ready for opening by hands.
However, due to its inherent construction, the abovementioned conventional back door closing device has some drawbacks. One of them is a weak point which has been exposed when, during closing movement of the back door, a foreign thing accidentally gets between the door and the vehicle body. In this case, the closing movement of the back door is enforcedly stopped applying a marked load to the electric drive unit 6. In fact, in such a case, the latch mechanism 5 must be awkwardly handled to release the striker of the back door for removing the foreign thing, or wiring of the electric drive unit 6 must be changed to run the motor of the unit 6 in a reversed direction for returning or lifting the back door to the released somewhat open position. However, these operation steps are difficult or at least troublesome.
Another weak point is the sway movement of the striker of the back door, which takes place when the back door is pulled down or pushed up by the closing device. Such sway movement of the striker is inevitably caused by the pivotal movement of the latch carrying plate 4. In fact, it has not been easy to provide the back door with a stable closed position when such pivotal drawing mechanism is employed.